/in/foo.c: In function 'main':
/in/foo.c:11:11: warning: implicit declaration of function 'paw' [-Wimplicit-function-declaration]
   y = 2 * paw(x, 2);
           ^~~
/tmp/ccu6CFPE.o: In function `main':
foo.c:(.text.startup+0x8b): undefined reference to `paw'
foo.c:(.text.startup+0xa4): undefined reference to `paw'
collect2: error: ld returned 1 exit status